Many protein amino acid sequences defy sequence analysis by the convention Edman Sequencing procedure. The difficulties arise, for example, through blocking or other modifications and through repetitive amino acid residues. We are using mass spectrometric methods such as collision-induced dissociation tandem mass spectrometry to obtain sequences from such intractable proteins. A manuscript describing this work has been published J.Godinho da Silva, Jr., O.L.T. Machado, C. Izumi, J.C. Padovan, B.T. Chait, U.A. Mirza & L.J. Greene "Amino acid sequence of a new allergenic 2S albumin storage protein from Ricinus communis which is part of a 30 kDa precursor protein" Archives of Biochem. & Biophys. 336 (1996) 10-18.